These were standardized across IBM products including the PC in 1987 with their
Common User Access project.
Many of them were copied from the earlier original Macintosh/Xerox ideas (1984) (with Command mapped to Control on PC keyboards), while there another large set were from other existing GUI apps at the time (such as Shift+Insert for paste). Which is why there are often two ways to do things. (e.g. Ctrl+Q and Alt+F4)
Microsoft found the Mac HIG/shortcuts appealing when creating Word and Excel over there and started using them in Windows before IBM and later (in the early 90s) brought them to DOS editors as well.
These new standards made their way to Unix with Motif and later CDE starting in 1988. Most Unix-like FLOSS desktops in the 90s copied this standard, as everyone knew them already.
Traditional Unix terminal editors preceded all this by a decade or two and weren't interested in changing. So that leaves just a few newcomers to take on the mantle of standard keybindings.
Early:
rhide, setedit (Turbo-vision editor clones, no longer packaged)
ne (nice editor, used this for years; not well known; tiny)
nano (must be extensively configured, support improved over the years; small)
Later:
vim (small to medium size)
emacs (gigantic)
tilde (not often packaged)
CUA modes were brought to these venerable editors but also incur a significant learning curve. Probably more than most folks want for their "notepad" clone.
Recent:
micro (in Debian and 20.04+)
Pretty darn big (12+ MB) and lacks a standard menu, but is otherwise excellent.
My recommendation is to use micro, unless you are in constrained environment such as OpenWRT, then use nano or ne.